近来，在项目中需要实现一个类似兴趣标签的选择器。由于标签的文字长度不定，所以标签的显示长度就不定。为了实现效果，就使用了UICollectionView来实现了每行的标签数量不定、cell的宽度自适应的效果。先在此分享出来：
1、自适应UICollectionViewCell
这里只是在自适应UICollectionViewCell上放一个和UICollectionViewCell保持一样大小的按钮，当选中和取消选中时改变按钮的文字颜色和边框颜色：
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#pragma mark---标签cell@implementation YLTagsCollectionViewCell-(instancetype)initWithFrame:(CGRect)frame{ if(self = [super initWithFrame:frame]){ self.backgroundColor = [UIColor clearColor]; _btn = [UIButton buttonWithType:UIButtonTypeCustom]; //此处可以根据需要自己使用自动布局代码实现 _btn.frame = CGRectMake(0, 0, frame.size.width, frame.size.height); _btn.backgroundColor = [UIColor whiteColor]; _btn.titleLabel.font = [UIFont systemFontOfSize:14]; _btn.layer.borderWidth = 1.f; _btn.layer.cornerRadius = frame.size.height/2.0; _btn.layer.masksToBounds = YES; [_btn setTitleColor:HEXCOLOR(0x666666) forState:UIControlStateNormal]; _btn.layer.borderColor = HEXCOLOR(0xdddddd).CGColor; _btn.userInteractionEnabled = NO; [self.contentView addSubview:_btn]; } return self;} -(void)layoutSubviews{ [super layoutSubviews]; _btn.frame = CGRectMake(0, 0, self.contentView.frame.size.width, self.contentView.frame.size.height);} -(void)setSelected:(BOOL)selected{ [super setSelected:selected]; _btn.layer.borderColor = selected?HEXCOLOR(0xffb400).CGColor:HEXCOLOR(0xdddddd).CGColor; [_btn setTitleColor:selected?HEXCOLOR(0xffb400):HEXCOLOR(0x666666) forState:UIControlStateNormal];} -(void)setHighlighted:(BOOL)highlighted{ [super setHighlighted:highlighted]; _btn.layer.borderColor = highlighted?HEXCOLOR(0xffb400).CGColor:HEXCOLOR(0xdddddd).CGColor; [_btn setTitleColor:highlighted?HEXCOLOR(0xffb400):HEXCOLOR(0x666666) forState:UIControlStateNormal];} @end |
2、UICollectionViewFlowLayout子类--YLWaterFlowLayout的实现
.h头文件
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#import <UIKit/UIKit.h> @class YLWaterFlowLayout;@protocol YLWaterFlowLayoutDelegate <NSObject>/**通过代理获得每个cell的宽度*/- (CGFloat)waterFlowLayout:(YLWaterFlowLayout *)layout widthAtIndexPath:(NSIndexPath *)indexPath; @end @interface YLWaterFlowLayout : UICollectionViewFlowLayout@property (nonatomic,assign) id<YLWaterFlowLayoutDelegate> delegate;@property(nonatomic,assign)CGFloat rowHeight;///< 固定行高 @end |
.m文件
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#import "YLWaterFlowLayout.h" @interface YLWaterFlowLayout()@property(nonatomic,strong)NSMutableArray *originxArray;@property(nonatomic,strong)NSMutableArray *originyArray;@end @implementation YLWaterFlowLayout#pragma mark - 初始化属性- (instancetype)init { self = [super init]; if (self) { self.minimumInteritemSpacing = 5;//同一行不同cell间距 self.minimumLineSpacing = 5;//行间距 self.sectionInset = UIEdgeInsetsMake(10, 10, 10, 10); self.scrollDirection = UICollectionViewScrollDirectionVertical; _originxArray = [NSMutableArray array]; _originyArray = [NSMutableArray array]; } return self;} #pragma mark - 重写父类的方法，实现瀑布流布局#pragma mark - 当尺寸有所变化时，重新刷新- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds { return YES;} - (void)prepareLayout { [super prepareLayout];} #pragma mark - 处理所有的Item的layoutAttributes- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect{ NSArray *array = [super layoutAttributesForElementsInRect:rect]; NSMutableArray *mutArray = [NSMutableArray arrayWithCapacity:array.count]; for(UICollectionViewLayoutAttributes *attrs in array){ UICollectionViewLayoutAttributes *theAttrs = [self layoutAttributesForItemAtIndexPath:attrs.indexPath]; [mutArray addObject:theAttrs]; } return mutArray;} #pragma mark - 处理单个的Item的layoutAttributes- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath{ CGFloat x = self.sectionInset.left; CGFloat y = self.sectionInset.top; //判断获得前一个cell的x和y NSInteger preRow = indexPath.row - 1; if(preRow >= 0){ if(_originyArray.count > preRow){ x = [_originxArray[preRow]floatValue]; y = [_originyArray[preRow]floatValue]; } NSIndexPath *preIndexPath = [NSIndexPath indexPathForItem:preRow inSection:indexPath.section]; CGFloat preWidth = [self.delegate waterFlowLayout:self widthAtIndexPath:preIndexPath]; x += preWidth + self.minimumInteritemSpacing; } CGFloat currentWidth = [self.delegate waterFlowLayout:self widthAtIndexPath:indexPath]; //保证一个cell不超过最大宽度 currentWidth = MIN(currentWidth, self.collectionView.frame.size.width - self.sectionInset.left - self.sectionInset.right); if(x + currentWidth > self.collectionView.frame.size.width - self.sectionInset.right){ //超出范围，换行 x = self.sectionInset.left; y += _rowHeight + self.minimumLineSpacing; } // 创建属性 UICollectionViewLayoutAttributes *attrs = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath]; attrs.frame = CGRectMake(x, y, currentWidth, _rowHeight); _originxArray[indexPath.row] = @(x); _originyArray[indexPath.row] = @(y); return attrs;} #pragma mark - CollectionView的滚动范围- (CGSize)collectionViewContentSize{ CGFloat width = self.collectionView.frame.size.width; __block CGFloat maxY = 0; [_originyArray enumerateObjectsUsingBlock:^(NSNumber *number, NSUInteger idx, BOOL * _Nonnull stop) { if ([number floatValue] > maxY) { maxY = [number floatValue]; } }]; return CGSizeMake(width, maxY + _rowHeight + self.sectionInset.bottom);} @end |
实现思路：在YLWaterFlowLayout中使用originxArray和originyArray两个个数组记录了每一个自定义YLTagsCollectionViewCell的位置x和y。
在 -(UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath方法中通获得与当前YLTagsCollectionViewCell临近的“上一个YLTagsCollectionViewCell”的位置和尺寸信息，将上一个cell的x加上上一个cell的width来得到当前cell的x。同时还要判断当前cell的x+width是否会超越出屏幕右边缘，如果超出，则表明需要换行显示了，这时候就要修改y的值了。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。
原文链接：https://blog.csdn.net/guojiezhi/article/details/51821990
